The use of certain block copolymers and their compounds in a number of end-uses and especially in footwear, is rapidly expanding. For example, in the footwear industry, certain block copolymer compounds are being used in large volume in the manufacture of a wide variety of shoes including canvas shoes, sport shoes, and dress shoes. The block copolymers may be utilized for this purpose for soling, foxing, innersoles and the like. These compositions are disclosed in Hendricks et al, U.S. Pat. No. Re. 28,236. In general, these shoe component compositions usually comprise a mixture of block copolymer, extending oil, polystyrene and possibly a filler. For the most part, these block copolymers have proved to be particularly advantageous in many respects, including flexibility, processability, lack of vulcanization requirement and wet slip. However, in certain respects, shortcomings have been noted. For example, commercial compounds should be free from delamination, free from elephant hide, and free from flow markings and marring. With respect to many styles in the casual and dress shoe area of footwear, one of the major shortcomings of the block copolymer compounds such as those referred to in U.S. Pat. No. Re. 28,236 is the lack of the smooth appearance. Present block copolymer compounds lack the smooth, relatively unblemished surface which is characteristic of compression molded vulcanized conventional rubber, injection molded polyvinyl chloride, or leather.
With regard to polyvinyl chloride, attempts have been made in the past to blend styrene-diene block copolymers with polyvinyl chloride. However, it has always been necessary in the past to include in the composition a PVC plasticizer. For example, in Potter, U.S. Pat. No. 3,801,529, the patentee adds a phosphate plasticizer having a solubility parameter between about 8.0 and 11.0 in order to compatibilize the block copolymer and PVC. Likewise, in Edmonston et al, U.S. Pat. No. 3,695,477, and Van Breen, U.S. Pat. No. 3,769,417, the patentees required the use of PVC plasticizers. However, the addition of these plasticizers to PVC and styrene-diene block copolymers effectively destroys the domain structure of the styrene end blocks in the block copolymer, drastically effecting the properties of the polymeric compositions. Accordingly, plasticized PVC/styrene-diene block copolymer blends are not useful for footwear. A new composition has now been found that eliminates the necessity for using typical PVC plasticizers.